1. Field of the Invention
The present invention relates to binoculars, and, more particularly, binoculars having a lens barrier for protecting an optical lens.
2. Related Art Statement
The human eye spacing, namely, the human inter-pupillary distance, varies considerably, depending on age, sex, and from person to person. To accommodate such variation, Japanese Unexamined Patent Publication No. 8-36135 discloses binoculars having a mechanism that adjusts the distance between a pair of lens barrels to accommodate users having a wide range of the inter-pupillary distance.
The above-mentioned binoculars have an eye spacing adjustment capability to change the relative position between a pair of lens barrels. Generally, the binoculars are kept with the spacing between their lens barrels narrowed in a closed state. During use, the spacing between the lens barrels is widened while the eye spacing adjustment is made at the same time. For example, Japanese Unexamined Patent Publication No. 8-36135 discloses binoculars having such an eye spacing adjustment capability.
The binoculars disclosed in Japanese Unexamined Patent Publication No. 8-36135 provides a lens barrier which is interlocked with the barrel spacing adjustment of barrels and protects each optical system of the lens barrels. The lens barrier substitutes for conventional lens caps, and serves as a protector for an objective lens unit and an eyepiece lens unit when the binoculars are in the closed state. When the binoculars are in the closed state, the lens barrier is moved to a position to cover the objective lens unit and the eyepiece lens unit, thereby protecting the lens units. During use, i.e., during eye spacing adjustment, the lens barrier is retracted from the lens units.
Among known binoculars of the type in which an optical system including an objective lens and an eyepiece lens is moved along the optical axis in response to the eye spacing adjustment of the lens barrels, some project the lens barrels, including the optical system, out of the body of the binoculars along the optical axis.
Referring to FIG. 10 and FIG. 11, one example of such binoculars is discussed. Binoculars 101 shown in FIG. 10 and FIG. 11 include a pair of lens barrels 103R and 103L having a pair of optical systems 105R and 105L, respectively. Each of the optical systems 105R and 105L has a pair of objective and eyepiece optical systems. The distance between the optical axes of the optical systems of the lens barrels 103R and 103L is adjustable, and the eye spacing adjustment is thus possible. FIG. 10 shows a closed state in which the lens barrels 103R and 103L are spaced by a minimum spacing. FIG. 11 shows that the lens barrels 103R and 103L are spaced by a maximum spacing.
In their body, the binoculars 101 includes an lens barrier member 102 that protects the objective optical system and the eyepiece optical system. The lens barrier member 102 includes a first barrier 102a that is moved to a position to cover the objective optical system when the binoculars 101 are in the closed state, a second barrier 102b that is moved to a position to cover the eyepiece optical system when the binoculars 101 are in the closed state, and a barrier connection member 102c for connecting the first barrier 102a and the second barrier 102b at their front and rear points.
Since the lens barrier member 102 also serves as the external housing of the binoculars 101, the lens barrier member 102 is affixed to the body of the binoculars, and their exposed portions, namely, the first barrier 102a and the second barrier 102b are planar.
Referring to FIG. 10, when the binoculars 101 are in the closed state, an objective lens and an eyepiece lens are respectively covered with the first barrier 102a and second barrier 102b of the lens barrier member 102.
When the binoculars 101 are in an operational state, i.e., when the spacing between the lens barrels 103R and 103L is widened to a maximum spacing as shown in FIG. 11, the first barrier 102a and second barrier 102b are retracted from their respective optical systems, and the fields of view are thus enabled.
As is the case with the binoculars disclosed in the Japanese Unexamined Patent Publication No. 8-36135, the binoculars having the above-referenced lens barrier suffers from the following problems.
Since the barrier member itself is made of a non-deformable material, space for retracting it is required. This affords designers less flexibility in the design of the binoculars and difficulty in the production of compact designs.
Moreover, when the lens barrier is in the retracted state, namely, during use, the binoculars offers no receiving space for the nose of the user.